Fire retardant polymer compositions



United States Patent US. Cl. 260-28 11 Claims ABSTRACT OF THE DISCLOSURE A fire retardant composition can be formed by use of a fire retarding agent of an arylhaloalkylalkyl phosphonate in combination with an organo halide compound. A typical example is cresyl-2-bromoethylmethyl phosphonate This is a continuation-in-part of Ser. No. 390,219, now abandoned, filed Aug. 17, 1964.

This invention relates to novel fire retardant polymer compositions, and to methods for rendering polymeric materials fire retardant.

The use of polymeric materials in industrial applications such as in making wire-coatings, pipes, conduits and other industrial moldings and extruded products is eX- panding each year. These and other uses are better served by polymer compositions that are fire retardant or flame resistant. Many prior art attempts to impart fire resistance to polymers by the use of additives have often adversely affected the desirable properties of the polymer due to the high proportions of fire retardant additive required to be used to achieve an adequate level of fire retardancy.

Accordingly, it is an object of this invention to pro vide fire retardant polymer compositions. Additionally, it is the object of this invention to provide polymeric materials for additive that not only impart fire resistance but also enhance or preserve other physical properties of these polymers.

In accordance with this invention there is provided a fire retardant polymeric composition wherein the fire retarding agent is an arylhaloalkylalkyl phosphonate in combination with an organohalide compound. Particularly enhanced fire retarding results are obtained when the ratio of arylhaloalkylalkyl phosphonate to organohalide compound is in the ratio of about 2 to 4 parts by Weight of arylhaloalkylalkyl phosphonate to 1 part of organohalide compound. The amount of fire retarding agents of this invention employed may vary over a wide range depending upon the exact degree of fire retardant properties desired in relation to other properties of the polymeric composition. However, it is desirable to employ the fire retarding agents of this invention in proportion from about 7 percent to about 40 percent and preferably from about 9 percent to about 30 percent by weight of the polymeric composition.

The aryl group of the arylhaloalkylalkyl phosphonate employed in this invention is preferably of a single aromatic ring (mononuclear). It is very desirable that the aryl group contain from 6 to 14 carbon atoms. Particularly preferred aryl groups include benzyl, phenyl and cresyl structures.

While all of the halogens having an atomic weight below 100 are suitable in this invention, bromine is particularly useful. Preferably, the haloalkyl of the arylhaloalkylalkyl phosphonate is a monohalogen alkyl wherein the alkyl contains from 1 to carbon atoms. Furthermore, the haloalkyl may be branched. The nonhalogen alkyl group 3,530,083 Patented Sept. 22, 1970 preferably contains from 1 to 6 carbon atoms and may be branched. Illustrative examples of the preferred arylhaloalkylalkyl phosphonates are cresyl 2 bromoethylmethyl phosphonate, phenyl-Z-bromoethylmethyl phosphonate, phenyl-2-bromopropylethyl phosphonate, phenyl- 2-bromoethylpropyl phosphonate, bis(4-phenyl-2-bromoethylmethyl phosphonate) 2,2 propane, bis (phenyl methylene phosphonate) 1,3 dibromo-2,2-propane and the like.

The organohalo compound suitable as a coacting fire retarding agent of this invention preferably contains either chlorine or bromine as the active halogen, although any halogen having an atomic weight below is satisfactory. It is preferable that these compounds contain at least 50 percent halogen. Illustrative of suitable organohalo compounds for use in this invention include but are not restricted to the following alkyls such as chlorinated paraflin waxes containing 5-0 or more percent chlorine and tetrabromooctane, alkenyls such as perchloropentacyclo (5.2.l.0 .0 .'D decane, cycloalkyls such as gamma 1,2,3,4,5,6 hexachlorocyclodecane, and liquid and solid chlorinated polyphenols.

The polymers embraced within the scope of this invention are homopolymers and copolymers of unsaturated aliphatic, cycloaliphatic and aromatic .hydrocarbons. Suitable monomers from which they may be made are ethylene, propylene, butene, pentene, hexene, heptene, octene, 2- methylpropene-1,3-methylbutene-l, 4-methylpentene-1, 4- methylhexene 1, bicyclo (2.2.1)-2-heptene, butadiene, pentadiene, isoprene, hexadinene, 2,3-dimethylbutadiene- 1,3,2-methylpentadiene-1,3 styrene, methylstyrene, 4-vinylcyclohexene, vinylcyclohexene, cyclopentadiene and the like. Especially beneficial results have been obtained when the polymers are polyethylene, polyethylene, polypropylene, polyester resin or polystyrene.

Two of the polymers of this group, polyethylene and polystyrene, have long been known in the art. Lowdensity (0.92 gram/cc.) polyethylene may be produced by the polymerization of ethylene at a pressure greater than twelve hundred atmospheres and at a temperature of one hundred to three hundred degrees centigrade. Lower pressures of about five hundred atmospheres can be used if a catalyst such as oxygen or benzoyl peroxide is added to the ethylene as described by Fawett et al., Chemical Abstracts, 32, 1362 (1938).

Polystyrene is readily produced by mass, solution or emulsion polymerization as described in The Technology of Plastics and Resins, Mason, 1. P'., and Manning, J. F., Van Nostrand Company (1945). The polymerization is promoted by the action of light and catalysts such as hydrogen peroxide, benzoyl peroxide and other organic peroxides. Suitable solvents for solution polymerization are toluene, xylene and chlorobenzene.

In recent years a new field of linear and stereoregular polymers has become available which are suitable for use in this invention. Polymers such as polypropylene are produced with organometallic catalysts and supported metal oxide catalysts as disclosed in great detail in Linear and Stereoregular Addition Polymers: Polymerization With Controlled Propagation, Gayloud, N. G., and Mark, H. F., Interscience Publishers, Inc. (1959). Monomers of the type disclosed hereinbefore are readily polymerized to solid polymers in the presence of a catalyst system comprising aluminum triethyl and titanium tetrachloride or titanium trichloride. The reaction is carried out in the presence of an inert hydrocarbon diluent, suitably purified of catalyst poisons, at a temperature in the range of fifty to two hundred and thirty degrees centigrade. At the conclusion of the reaction, the polymer can be recovered from the resulting solution or suspen sion by evaporation of the diluent, whereupon the poly- 4 mer is treated for removal of catalyst residues, for exby the present invention which provides a fire retardant ample, by washing with water or alcohol and acids. Metal composition for elastomeric compositions, which comoxide catalysts, such as chromium oxide supported on position requires no antimony. silica of alumina, are suitable for polymerizing l-olefins The components utilized in the composition of this containing a maximum of eight carbon atoms, with no r invention can be admixed by any one of several methods. branching closer to the double bond than the 4-position. O The additives can be introduced into a polymer when it Such polymerization may be carried out in the manner is dissolved in a suitable solvent. This procedure is espedescribed for the organometallic catalyst system. cially useful when it is desired to mix the additives during Other polymers also within the scope of this invention the polymer manufacturing process. When the polymer is include the polyesters, alkyds and paint vehicles, such as subsequently removed from the solvent, the additives are bodied linseed oil, nylon, diallyl phthalates and phthalates, intimately mixed with the polymer. Usually the additives and olycarbonates. Polycarbonates are thermoplastic are admixed with the polymer in the molten state at temresins formed from a dihydroxy compounds and a carperatures that can range from the melting point to the bonate diester. The more important commercial polycardecomposition temperature of the polymer. Alternatively, bonates are made from para, para isopropylidenediphenol the additives of the polymer are dry blended in finely diand phosgene. Polyesters are thermoplastic resins provided state so that an intimate mixture is obtained upon duced by the reaction of dibasic acids and dihydroxy comsubsequent molding or extrusion. pounds. The unsaturated polyesters can be further polym- The invention is illustrated by the following nonlimiterized by crosslinking. Alkyds are in many respects siming examples. Temperatures are expressed in degrees centiilar to polyesters, but alkyds utilize unsaturated fatty acids. grade and parts are by weight unless otherwise indicated. Resins within the scope of this invention include the con- In Example 1 through 22 the fire retardant or burning densation reaction products of phenol and aldehyde, e.g., characteristics of the molded polymer compositions were novolacs and thermoplastic polymers of bis-(4-hydroxytested in accordance with the American Society Testing phenyl)-2,2-propane and epichlorohydrin (tradename of Materials Test Procedure D-635-516 except that the Ph samples were molded in a 9-millimeter glass tube about 7 Flameproof polymer compositions are achieved by this inches longinvention without the need for the use of an antimony EXAMPLE 1 compound such as antimony oxide. In the usual fire re- I thi t t th po1ymer b or d was i it d f tafdant Polymenc composltlons an antlmony Compound thirty seconds. The burner was then pulled away and the is usually employed 1f fire retardancy is to be achieved length of time the olymer continued to burn was rewithout having a large proportion of the fire retardant corded. The procedure was then repeated on at least two material present in the polymeric composition. The use replicate rods. The test compositions and results obtained of antimony oxide in polymeric compositions is often 0bare given in the table below.

Parts Phosphonate Organohalide Self-extin- PO Y- guishing Example mer Type Parts Type Parts seconds (I) Polypropylene compositions:

1 85 Cresyl-2-bromoethylmethy1 phosphonate 10 Chlorinated paraflin (70% eh1orine) 5 Non-burning. 2 d 6%. d0 3% Do. 3 10 (am/30+. g 100 Chlorinated paraffin (70% chlorine). 5 +/45+/45+.

B g 981A C1'esgl-2-bl'olnoethylrnethyl phosphonate Perciloropentaeyclodecane 3 N dl iliurning.

z. 0..... o. 2 8 92% do 6? Tetrabromooctane 2/2/2. 9 01 Phenyl-Z-bromoethylmethyl phosphonate 6% Perchloropentaeyclodedane 2% Non-burning. 10 88 Phenyl-2-bromopropylmethyl phosphonateuz 9 do 3 34 11, 86% Bis( t-phenylQ-bromomethyl phosphonate)-2,2-propane 10 do 3% 2/2/2. (II) 11;olystyreriitzucorripositions:

13:: I:I:I:I::i ifhiiiiiatd paiahaii156%Ei1ibiii151l 545+. 14 15/17. 15 2% 4/10/14. 16..-" 88 Phenyl-2-bromopropylmethyl phosphonate 3 11/0/13/16. 17 86% Bis(4-phenyl-2-bromomethyl phosphonate)-2, propane... 3% 1/0/1. (III) Polyethylene compositions:

18 100 Burns. 19 95 Chlorinated paraifin (70% chlorine)... 5 45+/45+. 20 73% Cresyl-Z romoethylmethyl phosphona 20 Perchloropentacyclodecane 6% 2/0/0/10.

jectionable since the antimony compound tends to pigment the composition, greatly increases the specific gravity EXAMPLE 21 of the composition, tends to reduce the tensile strength In thlS eXaInple the heat distortion Properties of the of the composition and may occasionally tend to act as a compositions of this invention are compared with such curing agent. All of the above objections are overcome properties of other products.

A B o D Composition components, percent:

Polypropylene Antimony oxide Chlorinated parailin Cl) lcreliloropcntacyclodecanc Heat distortion point-6G pounds per square inch load, each bar l x x 5" (degrees centigrade average):

Single bar- 89. 5 106 98 102. 5 Three bars bolted together 06 110 100 NOTE.Thc signifies burning continued after time indicated.

From the foregoing examples, it is evident that the incorporation of arylhaloalkylalkyl phosphonate in combination with an organohalide compound into the ethylenically unsaturated hydrocarbon polymers imparts fire retardance to the polymers by slowing the burning rate in all cases, and by rendering the polymers self-extinguishing or nonburning at higher concentration.

(IV) Polyester compositions A polyester was prepared by reacting phthalic anhydride, maleic anhydride and proplyene glycol. This was then mixed with styrene to form a liquid unsaturated polyester resin. This polyester was used in Examples 22 and 23.

(V) Phenolic composition EXAMPLE 26-PHENOLIC RESIN Phosphonate Organohalide Self-extin- Parts guishmg polymer Type Parts Type Parts seconds Example:

22 Burns 23 85 Cresyl2-bromoethylmethy1phosphonate 12 Perchloropentacyelodeeane.-. 3 2/2/1.

In addition to the above illustrated organohalide compounds, other fire retardant compositions were prepared when the organohalide compound was gamma-1,23,45,6- hexachlorocyclohexane or a chlorinated phenol or polyphenyl such as Aroclor 5460 of a specific gravity of 1.670, manufactured by Monsanto Company, St. Louis, Mo.

A second polyester composition comprising chlorendic acid, maleic anhydride, neopentyl glycol, dissolved in styrene and polymerized to a low pouring content, was prepared.

This polyester was chosen because of its marginal fire retardance under the test conditions. Two 5-inch by S-inch laminates were prepared for comparative testing in accordance with the American Testing Materials Test Procedure D-757.

Laminate Ingredient:

Polyester, gm 100 100 2-bromoethyleresyhnethyl phosphonate, gm 0 10 Cobalt naphthenate (6%), phr 0. 0. 25 Lupersol DDM, phr 0.5 0.5

Both laminates had three piles of glass mat, hand laid up, and rolled to th inch thickness.

After curing at room temperature for 24 hours at 25 C., the test laminates were post cured at 110 C. in a forced draft oven for one hour. A Barcol hardness of 50-55 was obtained on both laminates after post cure. Specimens of each laminate were subjected to the ASTM D-757 Fire Retardance test with results as follows.

(with 2-bromoethylcresylmethyl phosphonate) Burning Distance rate, burned, inches] inches minute Specimen:

Paper N 0.

Weight of dry paper, grams 1. 13 1. 09 Weight of cured paper, grams 1. 70 1. 62 Percent cured add on 33. 5 31. 5 Char length, inches 4% 4% In each case the strips were self extinguishing with no afterglow. Strips treated in the same manner but without 2-bromoethylcresylmethyl phosphonate would have been completely consumed by the test.

It isalso within the scope of this invention to use heat stabilizers such as basic lead phosphite, dibutyl tin dilauryate, basic lead carbonates, and the like. Likewise, other additives such as carbon black, colored pigments and the like can be employed without departing from the spirit of the invention.

Various changes and modifications may be made in the method of this invention and in the composition ratios of this invention, certain preferred forms have been described, and equivalents may be substituted without departing from the spirit and scope of this invention. These modifications are to be regarded as within the scope of this invention.

What is claimed is:

1. A fire retardant polymeric composition wherein the fire retarding agent is in proportion from about 7.5 percent to about 40 percent by weight of the polymeric composition and is an arylhaloalkylalkyl phosphonate in combination with an organohalide compound wherein the halogen is selected from the group consisting of chlorine and bromine, the aryl group is mononuclear and contains from 6 to 14 carbon atoms, the haloalkyl group is a monohalogen alkyl containing from 1 to 10 carbon atoms, the nonhalogen alkyl group contains from 1 to 6 carbon atoms, and the organohalide compound contains at least 50 percent halogen.

2. A fire retardant polymeric composition according to claim 1 wherein the ratio of arylhaloalkylalkyl phosphonate to organohalide compound is about 2 to about 4 parts by weight of arylhalo phosphonate for each part by weight of organohalide compound.

3. A fire retardant polymeric composition according to claim 1 wherein the arylhaloalkylalkyl phosphonate is cresyl-2-bromoethylmethyl phosphonate.

4. A fire retardant polymeric composition according to claim 1 wherein the arylhaloalkylalkyl phosphonate is phenyl-Z-bromoethylmethyl phosphonate.

5. A fire retardant polymeric composition according to claim 1 wherein the organohalide compound is a chlorinated parafiin containing at least 50 percent chlorine.

6. A fire retardant polymeric composition according to claim 1 wherein the organohalide compound is perchloropentacyclo-(5.2.1.0 i .0 .0 )decane.

7. A fire retardant polymeric composition according to claim 1 wherein the fire retardant agent is a combination of about three parts of cresyl-Z-bromoethylmethyl phosphonate and one part of perchloropentacyclo- (5.2.1.0 .0 .0 )decane.

8. A fire retardant polymeric composition according to claim 1 wherein the polymer is selected from the group consisting of homopolymers and copolymers of unsaturated hydrocarbons, polyesters, alkyds, paint vehicles, nylon, diallylphthalates and phthalates, polycarbonates, phenol-aldehydes, and polymers of bis-(4hydroxyphenol)-2,2-propane and epichlorohydrin.

References Cited UNITED STATES PATENTS 2,666,078 5/1952 Ferguson 260-961 2,720,535 6/1951 Rosolapoff 260-961 2,725,311 5/1953 Kenaga 260-961 2,769,803 3/1953 Becker 260-805 3,046,236 2/1960 Jahn 260-2.5

MORRIS LIEBMAN, Primary Examiner L. T. JACOBS, Assistant Examiner US. Cl. X.R. 260-285, 45.7 

